1. Field of the Invention
The invention is generally related to the transport and storage of radioactive material and particularly to a cask that can be used for transporting or storing spent nuclear fuel.
2. General Background
Nuclear reactors require periodic replacement of the nuclear fuel. Fuel removed from reactors in naval vessels and some land based commercial reactors must be transported to a storage site. In some instances, there may be storage room at the site of the land based reactor. The United States Nuclear Regulatory Commission sets standards that must be met for casks that are used to transport or store spent nuclear fuel. Due to the different conditions that may be encountered during transport and static storage, separate standards are set for transport casks and for storage casks. These standards are respectively set forth in 10 CFR 71 and 10 CFR 72. Shipping casks must be able to withstand shock loads during transport while storage casks must be able to withstand temperature transients such as a fire external to the cask without transmitting additional heat to the inside of the cask. As a result, it is common to have separate casks for transport and storage. This presents the need for additional work in the form of transferring the fuel from one cask to another once the shipment has arrived at the storage site. If there is not an immediate need for reuse of the transport cask, then the transport cask which has a radioactive interior after use must also be stored until it is needed again.